BIOPHYSICAL PROPERTIES AND CLINICAL-APPLICATIONS OF MAGNETIC-RESONANCE-IMAGING CONTRAST AGENTS

Contrast enhanced magnetic resonance imaging (MRI) is a very versatile and effective technique for detecting and characterizing lesions, for identifying a variety of patho-physiological abnormalities, and for p roviding perfusion and functional information. The application of cont rast enhanced MRI to many clinical and research indications has emerge d because of the rapid evolution in imaging techniques, improved metho dology, and the development of efficient and specific contrast agents. Problems related to optimizing parameters and dosage have been due to complex interplay of relaxation times, biophysical mechanisms and acq uisition parameters. A knowledge of basic biophysical aspects is there fore essential for a full understanding of the results obtained for di fferent organs under different conditions, and for optimizing the imag e parameters and dosage of contrast agents. This article underlines th e biophysical basis of the effects of contrast agents in MRI, identifi es the problems involved in optimizing the parameters for maximum effi ciency; and presents a general overview of the clinical studies and re search applications in the central nervous system, perfusion abnormali ties, hepatobiliary system, musculoskeletal system and the gastrointes tinal tract. The section on perfusion studies includes a discussion of quantitative analysis and kinetic models describing the effects of co ntrast agents. Finally, a critical evaluation of the scope and limitat ions of contrast enhanced MRI is presented.